Embodiments of the invention relate generally to conformal coatings and, more particularly, to a method and apparatus for forming a patterned conformal structure for an electrical system.
Technological advancements in the area of electronic devices have experienced vast growth in recent years. For example, while cellular phones are becoming smaller and lighter, their features and capabilities are simultaneously expanding. This has caused an increase in the complexity and operation of the electrical components found in such devices and a decrease in the amount of space available for such components. Several challenges arise from such an increase in complexity of the electrical components and decrease in the amount of space available. For example, the reduction in size of the circuit board leads to increased congestion on the circuit board.
The decreased amount of space available and increased congestion of circuit components thereon poses a challenge with respect to radio frequency and electromagnetic interference (i.e., RFI and EMI) between components. That is, many electronic components radiate electromagnetic radiation, which may cause interference with other adjacent circuit board components and detrimentally affect the performance of the overall circuit assembly. As a result, shields have been used to prevent such components from causing such interference. Shields may also be desired to segregate areas on the circuit board/circuit assembly that operate at different potentials.
The most common RFI/EMI shields are box-type shields comprised of folded or stamped metal (i.e., metal cans, metal foil claddings, etc.) contoured to fit over a PC board or over individual circuit components thereon. Space must be allocated on the circuit board to accommodate these box-type shields, which reduces the space available for other components. That is, conventional box-type shields are bulky and take up a great deal of space and volume, a majority of which is an unused air gap between the circuit board and the shield. This can add to the overall thickness of an electronic device (e.g., a cellular phone).
As an alternative to box-type shields, conformal-type shields have recently been implemented for shielding circuit assemblies and shielding individual circuit components thereon. Typically, such shields are formed of a dielectric layer and a metal layer that are disposed onto the circuit assembly. A masking layer is applied over portions of the dielectric layer before application of the metal layer, such that a “patterned” metal layer can be formed on the dielectric layer that corresponds to circuit components of the circuit assembly. Use of such a masking layer, however, has its limitations. That is, for circuit assemblies having circuit components packed very tightly thereon, application of a masking layer may not be precise enough for accurate application/formation of the patterned metal layer.
Therefore, it would be desirable to design a patterned conformal structure, and method of manufacturing thereof, that can be implemented with circuit assemblies having tightly packed circuit components. The design would thus allow for a tighter packing density of components not possible with conventional box shields. It would further be desirable to provide an efficient method for manufacturing a patterned conformal structure that can eliminate use of a masking layer when patterning the metal layer to form conformal shielding structures.